Interpretive Summary: A new approach to soil testing shows intriguing results. Resin- extraction of four soils in the Northern Great Plains showed that extractability of important nutrients was being restricted by other nutrients. Further, this effect was related to soil mapping units. A study of Barnes, Buse, Langhei and Svea soils showed that each soil had a different suite of extractable nutrients. Important nutrients such as sulfur, boron and phosphorus were complexed by large amounts of calcium in the Langhei and Buse soils. Consequently, different fertilization strategies are needed to improve fertilizer use efficiency in these soils as broadcast applications of these nutrients will be less likely to improve plant growth than banded applications. Banded applications maintain more of the nutrient in forms taken up by plants. This work points the way to further plant nutrition studies by scientists. It also provides crop producers with an ability to identify plant nutrient needs more accurately. These, in turn, enable producers to improve soil and fertilizer use efficiency.

Technical Abstract:
Optimal resource management requires appropriate information. Advances in soil fertility and plant nutrition have lagged those in other aspects of plant science. Resin extraction of soil nutrients has the potential of identifying soil resource differences to which plants respond. A resin extraction technique was applied to samples of four soils (Barnes, Buse, Langhei, and Svea) collected on 23 sites in western Minnesota, eastern South Dakota and eastern and central North Dakota. Extracts were analyzed for 20 elements by inductively coupled plasma. Samples were also analyzed for texture, bicarbonate extractable P, pH, organic C and total N. Extracted suites of elements were unique for each of the soils. While traditional anions such as S, As, B, and P were usually found on anion exchange resins for three of the soils, as much as 90% of these extractable elements were found on the cation exchange resin for the Langhei soil. Large amounts of readily extractable cations such as Ca could account for complexation of anions. Resin-extractable P was correlated with bicarbonate extractable P, but the relationship was unique in each soil; this suggests that interpretations of test results by soil mapping unit are needed. Also, ratios of resin-extractable elements that correlate with plant response differed between soils and suggest that specific fertilizers and their placements affect resource use efficiency.